A new adaptive feedforward amplifier using imperfect signal cancellation

This paper describes a new adaptive feedforward amplifier for WCDMA system using an imperfect signal cancellation. Due to the complicated signal statistics, the distortion generated by the error amplifier is significantly reduced by the imperfect signal cancellation. Therefore, the performances of feedforward amplifier are improved with this new adaptation technique., especially for the modulated signals with a high peak-to-average ratio. For verification, a 2.14 GHz feedforward amplifier with 80 W output power has been implemented and tested with digital control circuits. The results, compared to the perfect signal cancellation, show more than 7 dB improvement of ACLR at 80 W output power. The efficiency is also improved from 7.5 % to 9 % at the same ACLR's.

[1]  Robert G. Meyer,et al.  A wide-band feedforward amplifier , 1974 .

[2]  V. Postoyalko,et al.  Sensitivity of distortion cancellation in feedforward amplifiers to loop imbalances , 1997, 1997 IEEE MTT-S International Microwave Symposium Digest.

[3]  Fadhel M. Ghannouchi,et al.  Digital implementations of adaptive feedforward amplifier linearization techniques , 1996, 1996 IEEE MTT-S International Microwave Symposium Digest.

[4]  Fadhel M. Ghannouchi,et al.  Pilotless adaptation of feedforward amplifiers driven by high-stress signals , 2001, Proceedings RAWCON 2001. 2001 IEEE Radio and Wireless Conference (Cat.No.01EX514).

[5]  Bumman Kim,et al.  Digital controlled adaptive feedforward amplifier for IMT-2000 band , 2000, 2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017).

[6]  P. B. Kenington,et al.  The Specification of Error Amplifiers for use in Feedforward Transmitters , 1992 .

[7]  K. Horiguchi,et al.  A high efficiency feedforward amplifier with a series diode linearizer for cellular base stations , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[8]  J. S. Kenney,et al.  DESIGN CONSIDERATIONS FOR MULTICARRIER CDMA BASE STATION POWER AMPLIFIERS , 1999 .